PLA

One of the most common problems with PLA is oozing. Since the filament flows relatively easily when compared to the other materials, it has a tendency to continue flowing during travel movements at the end of a segment. This creates strings or hairs on your part, and dialing in your retraction settings is the best way to combat this behavior! Different brands of PLA and different printers may need slightly different retraction settings, so you may need to experiment to find the best value for your printer. Simplify3D added a very useful feature in Version 4.0 that can help with this, by allowing you to quickly try dozens of different settings, and then look at the final part to determine which one worked the best on your specific setup. For example, you could setup two vertical pillars which are printed side-by-side to evaluate stringing when moving back-and-forth between each pillar. Then go to Tools > Variable Settings Wizard and choose how you want to adjust your settings during the print. For example, you could try a different retraction distance for each 20mm section of the print and then pick the value that works best in the end. For more tips on how to reduce stringing and oozing, be sure to check out our Print Quality Guide which contains an entire section dedicated to this issue: How to Reduce Stringing and Oozing.

Cooling is one of the most important aspects of printing with PLA. Having a dedicated part cooling fan makes a huge difference in the quality of the printed parts. The freshly extruded plastic needs to cool down below the glass transition temperature as quickly as possible. This will prevent the plastic from stringing and producing other artifacts. We recommend setting the fan to 100% throughout the print, except for the first 1-2 layers where you want to form a strong bond with the print bed. Simplify3D also includes a useful option on the Cooling tab of your process settings that can automatically reduce the print speed for small parts, ensuring that the layers have sufficient time to cool. This can greatly improve the print quality by allowing the layer to solidify before printing the next layer on top of it. This setting can be found on the Speeds tab of your process settings.

This is a great tip for any filament, but is especially useful for PLA which often contains different combinations of additives depending on the manufacturer. These different additives can lead to variations in printing temperature between 190-230 degrees Celsius. If you are not printing at the right temperature this can lead to several print quality issues including oozing, stringing, and under-extrusion. PLA can also be combined with different fills like metal, wood, and fiber that give it different characteristics than a standard homogeneous PLA. These may require different settings or even different hardware. Be sure to check with the manufacturer of your filament to verify the optimal temperature to use for your specific filament. If you have trouble with stringing, try reducing this temperature by 5-10 degrees, which will help prevent the excess oozing. If you’re struggling with under-extrusion, try increasing the temperature by 10 degrees so that the material flows more easily through the nozzle.